The service sector generates 75% of Panama’s gross domestic product (GDP). Services are related to canal traffic (Figure 22), public administration, mineral extraction (Figure 23) offshore banking and other services. Fishing and agriculture accounted for less than 10% of the GDP prior to 1990s [1]. Prior to the 1990s, U.S. military forces stationed in Panama supported 5% of GDP. After U.S. troop withdrawal, the Panamanian government lost millions of dollars. The Panamanian government has re-developed (Figure 24) the previously U.S. controlled properties in the Panama Canal Zone and prime real estate in Panama City. The government repaired the road and rail system and has promoted ecotourism. China, Latin America, Middle East and the U.S. have all invested in

Panama which has boosted economic growth. Starting in 2020 COVID-19 has disrupted re-development of former U.S military bases and increased the rural and urban crime rate in Panama.

Land tenure was enacted in 1962. Now modern commercial agricultural enterprise are adjacent to subsistence and seminomadic agriculture. Common agricultural products are sugarcane, rice, bananas, plantains, oranges and corn. Livestock includes pigs, cattle and poultry. There is little use of Panama’s valuable and abundant forest resources. Few native trees are used for industrial purposes. Mahogany, cativo, tropical cedar and other woods supply sawmills with some log exports. Some large rainforest tracts have been burned, felled and replaced by cattle pastures. Shrimp and lobster are among Panama’s most important exports and fishing has become a commercial venture. Fish (anchovy and herring) are caught in shallow waters of the continental shelf in the Gulf of Panama. Aquaculture is being successfully developed. Lobsters are caught off San Blas and Bocas de Toro on the Atlantic side.

Salt, limestone and clay are the leading mineral products (Figure 23). On a small scale gold, manganese and ferrous sand are also being mined. There are significant deposits of copper, phosphates, bauxite, and coal that have been minimally exploited [3]. Construction material resources include stones and gravel. Petroleum reserves are found on continental shelves in both the Pacific Ocean and the Caribbean Sea.

Electricity was distributed by state-run Institute of Hydraulic Resources, but was privatized in 1998. Much of the electricity comes from hydroelectric dams. The first electric generating plant was opened at La Yeguada in 1975, on the Chepo River in 1976, and at La Fortuna in 1984. Modern Panama industrial development began after WWII. The leading industries are food processing (sugar, fish, cacaco and bananas), production of natural gas and electricity and oil refining. Other products include clothing, shoes, leather goods, alcoholic beverages, paper, chemical, tobacco and cement products [3].

The Istmus of Panama was an ideal environment for mosquitoes [11] [12]. Yellow fever was the most feared of the scourges afflicting humans in Panama. Many workers thought the “miasmas” or heavy, bad-smelling vapors that rose out of the wetlands and swamps were the cause of diseases. The “miasma theory” of disease causality persisted from the 13^th century through the 19^th century, even with the discovery that mosquitoes (Aedesaegypti) carried the disease which hindered the Gorgas sanitation plan in 1904. The initial symptoms of yellow fever were a headache, fever and back pain, followed by prostration, bleeding and decreased urine production. Finally, delirium and black vomit brought death (Figure 31) within a few days. During the July 10, 1904 to November 22, 1905 time period, there were 246 cases. Most patients were treated at the Anoco Hospital (Figure 32) in Anoco, Panama [8].

The successful construction of the Panama Canal required the control of malaria. Sir Robert Ross, a British Doctor, discovered in 1907 that malaria was transmitted by mosquitoes. In Cuba, regulations were put into effect in 1899 by

the U.S. Army Medical Officer to control of yellow fever which consisted of extensive drainage to reduce breeding of mosquitoes and putting screens on houses. The Isthmus of Panama was an ideal environment for mosquitoes [11] [12]. The same concept was applied a few years later in Panama [8]. In June 30, 1904 the Sanitary Department was created and headed by Colonel Gorgas. He applied a military style campaign to eradicate mosquitoes, which, while costly, greatly reduced the breeding of mosquitoes and yellow fever and malaria transmission [8].

The white arsenic (As) used between 1913 and 1932 to kill the floating plants in both Lake Gatun and the Panama Canal is an extremely toxic soluble white solid made by burning arsenic (As₂O₃). Arsenious oxides, commonly known as white arsenic, are obtained as a by-product from the smelting of lead, copper, and certain other metals by roasting of sulfide ores and arsenopyrite. Sweden was the United States primary source of white arsenic in the 1960s. The inorganic forms, including arsenate/arsenite (found in soil, water and food) and arsenic trioxide, are human health concerns [3].

The USDA, Forest Service [7] conducted chemical and pesticide dip stake studies in 1943, 1946 and 1952 on Barro Colorado Island for termite control. These chemicals included lead arsenate, sodium arsenite, DDT and chlordane. Arsenate and arsenite are water soluble and can either move in surface runoff water or leach into the groundwater. In 1963 the Curundu Jungle Test Site at Fort Clayton on Pacific side was used in additional stake tests.

Malathion which acts as acetyl cholinesterase inhibitor is an organophosphate insecticide that affects the nervous system and increases the risk of Parkinson’s disease [11]. Malathion was registered for use as an insecticide in the United States beginning in 1956. Malathion ground applications were usually made by truck mounted fogging equipment which was true in Panama Canal Zone.

During the American Vietnam War (1965 to 1973), a large number of troops came down with malaria [13]. To kill mosquitoes that carried malaria in South Vietnam, DOD converted aircraft that were previously used to spray Agent Orange and other tactical herbicides to spraying malathion, an insecticide as part of Operation Flyswatter. However, starting in 1970 C-123 aircraft, previously used to spray Agent Orange and other tactical herbicides including Agent Blue, were re-located to the United States Air Force Reserved units as well as international airfields. In 1970 three C-123 aircraft that were previously contaminated with TCDD and As during Operation Ranch Hand in South Vietnam [14] before they were sent to Howard Air Force base in Panama [14]. These aircraft were used to spray malathion on the Panama Canal Zone from 1970 to 1973.

DDT, dichlorodiphenyltrichloroethane, is colorless, tasteless and an almost odorless crystal chemical compound. DDT was one of the first chemicals used as a widespread pesticide. After WWII it was used in agriculture and households until it was banned in the United States in 1972. Austrian chemist Othmar Zeidler first synthesized DDT in 1874. Swiss chemist, Paul H. Muller discovered the DDT insecticidal action in 1939. Paul H. Muller was awarded the Nobel Prize in Medicine and Physiology in 1948. DDT was used during the last half of WWII to limit the spread of insect-born malaria and typhus [8]. DDT became available for public sale in October of 1945. Government and industry promoted its use as a household and agricultural pesticide. The 1962 publication of Rachel Carson’s book “Silent Spring” [15] focused the opposition on DDT. The book questioned the practice of broadcasting potentially dangerous chemicals into the environment without an investigation of their health and environmental effects. The book’s author claimed DDT caused cancer. The U.S. military removed DDT from the supply chain in 1965 due in part to resistance of body lice to DDT and replaced it with lindane [16]. Agricultural use of DDT was banned in the United States in 1972. However, DDT was sprayed extensively in the Panama Canal Zone (not officially part of the United States) after 1972. DDT remained effective in killing mosquitoes and dramatically reduced malarial infections. From the 1950s to the 1980s more than 40,000 ton/yr of DDT were used in worldwide agriculture and mosquito control. During this time period, the World Health Organization (WHO) was the largest purchaser of DDT in the World. DDT was manufactured by 15 different chemical companies, including Monsanto, Ciba, and Montrose Chemical. Worldwide use was banned in 2004.

2,4-Dichlorophenoxyacetic acid (2,4-D) is an organic compound [17] with the chemical formula C₈H₆Cl₂O₃ (2,4-D). This systemic herbicide has growth regulator effects that selectively kill plants by causing uncontrolled growth in most broadleaf weeds. The herbicide has been commercially available since 1945. The herbicide 2,4-D is one of the most widely used and oldest defoliants in the world. After the patent expired it was produced by many chemical companies. There are over 1500 herbicide products which contain 2,4-D as the active ingredient. It is widely used as a commercial lawn herbicide and as a weed killer on cereal crops and orchards.

The 2,4-D discovery occurred during World War II (late 1930s) independently by four groups in the United Kingdom and the United States under wartime secrecy. The initial publication of 2,4-D’s ability to control broadleaf weeds as a selective herbicide came in 1944. The herbicide 2,4-D was one of the ingredients in Agent Purple and was used in the Malayan Emergency. 2,4-D was also contained in other tactical herbicides: Agent Orange, Agent White, Agent Green, and Agent Pink which were used during the Vietnam War [13]. Agents Purple, Pink, Green and Orange also contained 2,4,5-T contaminated with TCDD (2,3,7,8-Tetrachlorodibenzodioxin) which caused adverse human health effects. 2,4-D kills both terrestrial and aquatic broadleaf weeds [17]. It was and is still used to control aquatic weeds in the Panama Canal and Lake Gatun which interfered with boating and shipping. In other waterways it was used to unclog irrigation canals and hydroelectric equipment. Some ester forms of 2,4-D are highly toxic to fish, moderate toxicity to birds and mammals, and slightly toxic to aquatic invertebrates [15]. Men, often Panamanians, who worked with 2,4-D are at risk for abnormally shaped sperm and have fertility problems.

Under most environmental conditions 2,4-D esters and amine salts are not persistent [15]. The herbicide 2,4-D is broken down by microbes in soil in a process involving hydroxylation. A number of 2,4-D degrading bacteria have been isolated and characterized from a variety of environmental habitats. Breakdown is pH dependent, but is highly mobile and leaches as a result of low affinity in mineral soils and sediment.

In an aerobic mineral soil the degradation of 2,4-D is rapid (half-life of 6.2 days) [18]; however it has a 15-day half-life in anaerobic mineral soils. In anaerobic aquatic environment, 2,4-D was moderately persistent to persistent (half-life of 41 to 333 days) [18]. The herbicide 2,4-D has been detected in streams and shallow groundwater but at low concentrations in United States rural and urban areas. No data are available for the Panama Canal Zone.

A chlorophenoxyacetic acid herbicide 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) is a synthetic auxin created to defoliate broad-leafed plants. It was developed in the late 1940s and was slowly phased out in United States in the late 1970s due to toxicity concerns and not manufactured after 1985 [19]. The herbicide 2,4,5-T itself is toxic. An intake rated of 10 mg/kg/day 2,4,5-T can cause adverse alterations in organisms. In addition, the manufacturing process for 2,4,5-T can contaminate this herbicide with unknown amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

The half-life of 2,4,5-T is similar to 2,4-D. The degradation of 2,4-D and 2,4,5-T are rapid (half-life of 6.2 days) in an aerobic mineral soil [18] but have a 15-day half-life in anaerobic mineral soils [18]. The herbicides are moderately persistent to persistent (half-life of 41 to 333 days) in anaerobic aquatic environments.

The by-product 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an unanticipated contaminant created during the manufacture of the herbicide 2,4,5-T. TCDD has a very long half-life and does not degrade easily. Each batch of commercially available 2,4,5-T herbicide has an average concentration of about 2 to 3 ppm of TCDD but can vary between 0.05 ppm to 50 ppm [19]. TCDD is an endocrine disrupter and can cause a variety of chloracne, cancers and developmental and reproductive effects.

TCDD is not water soluble and can adhere to leaf surfaces, organic material, fine soil particles and sediments which can be carried downstream by runoff water flow into wetlands, ponds and lakes such as Lake Gatun. Dioxin TCDD can bio-accumulate in aquatic species and become bio-magnified throughout the food chain via mollusks, fowl and fish eaten by humans and other animals [20].

The Lake Gatun and Panama Canal sediment should be checked for concentrations of TCDD which is probably bound to organic materials and soil particles within the lake, wetlands, waterways and ponds. TCDD could be diluted in Lake Gatun depending on the distance from shore. TCDD can be eliminated from the surface of Lake Gatun waters by photo degradation. The half-life of TCDD in the clear waters of Lake Gatun is based on high intensity of ultraviolet radiation hitting the lake waters. The largest fraction of TCDD in most waters binds to detritus, algae, organic materials and mineral matter. These TCDD particles do not remain in the water column but attach to and are deposited with the sediment. By measuring particle concentration in water and their rate of settling the rate of loss can be calculated. Very little TCDD is dissolved in water due to its hydrophobic nature. TCDD in the sediment particles can be returned to the water when sediment is re-suspended [21].

Sediment re-suspension occurs in Panamanian lake waters which are shallow and easily churned by wave and wind action [22]. TCDD is ultimately eliminated from the aquatic system via microbial degradation within sediments or when TCDD particles found in sediments are buried deeply in waterways or lakes [22]. Degradation by anaerobic microorganisms in sediments or permanently saturated soils can occur over time periods of 10, 20, 50 years to centuries [18].

TCDD in the food chain affects both Panamanian capacity to derive livelihoods from fish and other aquatic plants and animals and their own health. The half-life of dioxin varies depending on site conditions. In surface soil the half-life is between 1 and 3 years when fully exposed to sunlight. In an aerobic soil the half-life is between 11 and 15 years and estimated to be 20 to 50 years or more when buried in the tropical anaerobic soil. In waterways and lake sediments the half-life can be more than 100 years [18].

About 39.4 million liters of Agent Orange were sprayed during the course of the Vietnam War. Agent Orange had a short half-life and rapidly degraded, remaining toxic for only a short period, days or a few weeks at most. The tropical vegetation quickly regrew requiring repeated applications. Unfortunately, Agent Orange and the defoliants with 2,4,5-T in their formulations had an unanticipated contaminant or by-product 2,3,7,8-Tetrachlorodibenzodioxin (TCDD), which had a very long half-life under anaerobic conditions and did not easily degrade. Many batches of Agents Pink, Purple, and Green had higher concentrations of TCDD than early batches of Agent Orange [19]. However, later batches of Agent Orange TCDD in the late 1960s had much greater TCDD levels as a result of higher manufacturing temperatures [13].

The term “dioxin” represents a class of about 300 chemicals which are formed (usually unintentionally) when chlorine at very high temperatures binds to a molecule that contains carbon (C). This occurs in the bleaching of paper/pulp and chemical manufacturing processes. In the late 1960s, the U.S. military demanded greater quantities of Agent Orange from private chemical companies (there was a shortage which resulted in Agent White use, without 2,4,5-T and the by-product TCDD, being used), the manufacturing processes were speeded up by companies such as Dow Chemical and Monsanto (company correspondence included in the 1984 Vietnam Veteran lawsuit discovery documents) by raising the temperature about 5 degrees centigrade which increased the amount of 2,3,7,8-Tetrachlorodibenzodioxin (TCDD) in the herbicide by up to three thousand times. As noted earlier, the average concentration of TCDD in similar commercial herbicide in each batch of 2,3,5-T was about 2 - 3 ppm but the range ran from 0.05 ppm to almost 50 ppm. So, the use of tactical grade Agent Orange manufactured to “military specifications” in the late 1960s had considerably more TCDD in it than the commercially available herbicide and would have greatly increased the TCDD levels in the Panama Canal Zone if it had been offloaded and used.

Apparently, the chemical companies asked the DOD if the higher levels of the contaminant TCDD posed a problem. The DOD leadership team suggested that they needed more Agent Orange for the war effort and favored any manufacturing process which produced more Agent Orange in less time [19]. Since the Agent Orange was going to be sprayed primarily on the Viet Cong, with some collateral damage, it was apparently not seen by the military (in the middle of the American Vietnam War) as a problem. Furthermore, adding to the decision process was a significant shortage of Agent Orange. Consequently, the private chemical companies, who were under orders from the U. S. government and military to produce vast quantities of Agent Orange, complied. If they had not complied during war time they were at risk of being taken over by the U. S. government and military. So, if tactical herbicides with a different formulation and higher levels of TCDD were used instead of commercial herbicides in Panama Canal Zone, the amount of TCDD applied to the landscape could have been increased by as much as 3000 times and would have contributed to even higher TCDD levels in the Panama Canal Zone soils and water. Soil and sediment sampling of the military base grounds, Panama Canal and Lake Gatun should be considered to demonstrate that only commercial herbicides with low TCDD levels (less than 50 ppm) were used in the Panama Canal Zone. Commercial spraying should have only resulted in trace amounts of TCDD remaining in the soils, sediments and water.

The most toxic of all the dioxins and dioxin-like compounds is TCDD [23]. The U.S. National Academy of Sciences estimated the Vietnam War defoliation project released an estimated between 110 and 180 kilograms of TCDD into South Vietnam environment [19] [23]. The US National Toxicology Program (NTP) and the International Agency for the Research on Cancer both listed dioxin TCDD as known human carcinogens. Dioxins are endocrine disrupters and can cause certain chloracne, cancers and developmental and reproductive effects. Although TCDD is not water soluble and can adhere to leaf surfaces, organic materials, fine soil particles, and sediments that can be carried by runoff into downstream waters and deposited in wetlands, ponds, and lakes [24] [25]. In this way, TCDD can bio-accumulate in aquatic species and can become biomagnified throughout the food chain via mollusks, fowl and fish eaten by humans and other animals [20] [24].

A recently released report of the United States Government Accountability Office (GAO) focused on the actions needed to improve the accuracy and communication of information regarding storage and testing locations of Agent Orange outside of Vietnam [14] including Kelly Air Force Base in Texas [26]. This GAO report confirmed that the Military Sea Transportation Service directly chartered merchant vessels to carry tactical herbicides through the Panama Canal during the Vietnam War. These tactical herbicides, including Agents White, Blue and Orange, were stored vertically on pallets in internal storage compartments on the vessels. There is no official evidence to show the tactical herbicides were ever offloaded in Panama [27].

However, there are other documents which support the presence of similar commercial herbicides 2,4-D and 2,4,5-T containing with unknown amount of dioxin TCDD. A December 1976 Environmental Sampling Report for the Panama Canal Zone showed chlorophenoxy herbicides were detected in the soil samples from the Canal Zone [14]. Chlorophenoxy herbicides are identified by the Centers for Disease Control and Prevention as 2,4,5-T based herbicide containing TCDD [14]. In the 14^th Annual Meeting of U.S. Army Corps of Engineering report on the “Aquatic Plant Control Research Program” there is a section which notes the June 1978 initiation of large-scale testing of 2,4-D on water hyacinth [4] [5]. Since commercially available 2,4-D was used on military bases in Panama Canal Zone this herbicide would have been available for testing on the hyacinth in Lake Gatun and could have been used as a test site.

The U.S. government and military have for more than 60 years maintained those tactical herbicides such as Agent Orange and Agent Blue were never “off loaded in the Panama Canal Zone nor aerially sprayed on the Tropical Forests of the Panama Canal Zone” [28]. This statement has over the years been challenged by many Panama Vietnam Era Veterans who claimed that they handled and/or were exposed to toxic chemical sprays [14]. Panama veterans who were exposed to commercial herbicides including 2,4,5-T containing unknown amount of dioxin TCDD, have filed for VA benefits but have been repeatedly denied benefits [12] since the tactical herbicides were not officially offloaded and/or applied to the Panama Canal Zone landscape [27]. However, commercial herbicides containing 2,4,5-T and an unknown amount of dioxin TCDD were used on the U.S. military base grounds [9] [10]. These herbicides were very similar (composition and strength) but often lower in TCDD than the restricted use tactical herbicides being transported through the Panama Canal Zone to the South China Sea for use during the Vietnam War. The U.S. government and military declared, on the official record [27], that tactical herbicides were never used in the Panama Canal Zone. However, DOD was not really claiming that “unrestricted commercial herbicides” were never requisitioned, offloaded, handled and applied by military personnel to the military base grounds and perimeter fences [9] [10] [12] at the direction of the Base Civil Engineer Commanders.

It is also assumed that any aerial spraying done by aircraft only involved commercially available herbicides including 2,4-D and 2,4,5-T containing dioxin TCDD and arsenic [11]. However, three C-123 aircraft that were used to spray malathion in the Panama Canal Zone may have been previously contaminated with tactical herbicides in other theaters of operation including South Vietnam. After President Nixon stopped Agent Orange spraying in 1970, three C-123 aircraft previously used to spray tactical herbicides in Vietnam [28] and contaminated with tactical herbicides (including Agent Orange, Agent White and Agent Blue) residues in their spray tanks, were relocated via a transport ship in 1970 to Howard Air Force base in Panama. These TCDD and As contaminated C-123 planes were used from 1970 to 1973 to spray malathion in the Panama Canal Zone [28]. This may have resulted in trace amounts of tactical herbicide Agent Orange (TCDD) and Agent Blue (As) [29] being added to the soils and water of the Panama Canal Zone.

A GAO review of DOD and VA documents [30] identified multiple examples of incomplete and inaccurate information on the DOD’s list of tactical herbicide test and storage sites such as Kelly Air Force Base in Texas. GAO obtained command histories and original DOD reports which provided operational details about the procurement, distribution, use, and disposition of Agent Orange [20] and its components, 2,4-D and 2,4,5-T containing unknown amount of dioxin TCDD. GAO concluded that there was extensive documentation on the herbicide management program at Kelly Air Force Base for the American Vietnam War time period and more specifically years 1966-1973. According to an Air Force Logistics Command’s Office of History monograph, the command directly responsible for managing Agent Orange was the Directorate of Aerospace Fuels at the San Antonio Air Material Area located at Kelly Air Force base [14]. During the Vietnam War Kelly Air Force Base was also a subcomponent of the U.S. Air Force Logistics Command.

GAO documentation shows that quantities of the two components of the tactical herbicide Agent Orange were stored at Kelly Air Force Base in Texas in 1972. There were 38,940 gallons of 2,4,5-T containing TCDD and 106,260 gallons of 2,4-D stored on the base [14]. The uneven quantities of these two herbicides suggest that not all the tactical herbicides in storage were in the pre-mixed to form of Agent Orange, Herbicide Orange or Butyl Ester. Perhaps Agent White a tactical herbicide used when Agent Orange was in short supply, which contains only 2,4-D but not 2,4,5-T with TCDD was also in Kelly Air Force base storage [14]. After the American Vietnam War ended in 1973 the tactical herbicide Agent Orange with 2,4-D and 2,4,5-T containing an unknown amount of dioxin TCDD herbicide components in the stock pile was apparently transferred to the United States Department of Agriculture (USDA) for brush control which could have been one of the sources of the herbicides used by the USDA, Forest Service in the Western United States in the 1970s to control the brush and broadleaf weeds after clear cutting. This was the subject of a 2021 PBS documentary Independent Lens on “People vs. Agent Orange” [31] and a Vietnam Veteran News podcast 2086 by Mack Payne [32]. In order for the tactical herbicides stored at Kelly Air Force base to be transferred to the USDA for agency use in the Western United States it appears that the tactical herbicides would have had to be reclassified from formulated “Military Specifications” [33] to formulated “Federal Specifications” before being approved for use and applied by the USDA, Forest Service, timber company and chemical company partners in the Western United States to prevent shrub and broadleaf weed regrowth competition with trees on clear cut public forest lands.

GAO records also show that approximately 173,910 gallons of the tactical herbicide Agent Blue [14] containing cacodylic acid (As) was also stored at Kelly Air Force base. It is not clear how this massive amount of arsenic-rich Agent Blue was disposed of after the American Vietnam War officially ended in January of 1973. It could have been transferred to USDA, including the Forest Service, for brush control along with the Herbicide Orange (Agent Orange) components 2,4-D and 2,4,5-T containing TCDD. If DOD transferred the tactical herbicide Agent Blue to USDA, the transfer of a herbicide, originally formulated to “Military Specifications” [33] to a federal agency with only the ability to use herbicides formulated to “Federal Specifications”, for another federal agency use to control brush and would have required Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) approval. If Agent Blue was applied by the USDA, Forest Service in the 1970s, arsenic, which does not have a half-life, would have remained in the Western United States soils. However, it is not clear if the tactical herbicide, Agent Blue, was ever transferred by the DOD, with proper FIFRA approval, from Kelly Air Force base chemical stockpile to USDA along with other tactical herbicides including Agent Orange with 2,4-D and 2.4.5-T containing an unknown amount of TCDD for brush control which could have been one of the sources of the herbicides used by USDA, Forest Service in the Western United States [31] in the 1970s.

If Agent Blue was not used on Federal lands in Western United States, then what happened to the 173,910 gallons of Agent Blue that were stored at Kelly Air Force base after the tactical herbicide was no longer needed in South Vietnam? Was Agent Blue destroyed in Kelly Air Force base burn pits? If so the smoke coming from the burn pits would have become an environmental problem since the particulate and ash would have contained toxic As contaminants and aerosols. The military base personnel could have been exposed to and inhaled arsenic laden smoke. Was it buried in the soil at Kelly Air Force base? If so, the water soluble As would eventually leak from the barrels in the last 50 years and into the groundwater. If so, the military base personnel could have been exposed to arsenic and some Kelly Air Force Base Vietnam Era Veterans [12] have already filed VA claims for benefits as a result of exposure to either TCDD or arsenic. The fourth option would have been to transport the Agent Blue to Davis-Monthan Air Force Base in Tucson, Arizona for weed control around the aircraft and perimeter fence (Figure 33 and Figure 34). This would have been in

addition to the Agent Blue barrels shipped from South Vietnam directly and from Johnston Island indirectly [30] between 1972 and 1977. So how did the DOD use up or destroy all of the arsenic based Agent Blue left over from the American Vietnam War, including the storage stockpile at Kelly Air Force base in Texas, after President Nixon stopped the spraying of all tactical herbicides in 1971?

The herbicides 2,4-D and 2,4,5-T containing low levels of TCDD were commercially available and thus could be ordered and used separately by any Federal Agency, including the military and shipped to and used on the Panama Canal Zone military base grounds. While there are no documents which prove tactical herbicides, such as pre-mixed Agent Orange, were ever offloaded in Panama Canal Zone [33] and/or sprayed on the tropical forests and islands in the Panama Canal Zone, however, there are commercial ship transport records, which show commercial herbicides, Orange, Ester-Butyl, 2,4-D and 2,4,5-T containing the contaminant TCDD were used on military bases in the Panama Canal Zone [33]. Even if tactical herbicides were never off loaded and sprayed in the Panama Canal Zone the commercial herbicides including 2,4,5-T by-product containing unknown levels of TCDD were used on the military base grounds and perimeter fences by military base personal to control the vegetation and insect pests and would have added TCDD to the Panama Canal Zone environment. There is evidence that DDT and malathion (first registered in 1956) [17], 2,4-D and 2,4,5-T with the contaminant dioxin TCDD were sprayed on Panama Canal Zone highways, structures, military grounds and perimeter fences using sprayers mounted on trucks in the Panama Canal Zone.